This invention relates to an improvement in the automobile exhaust gas purifying apparatus and more particularly in the device for supplying air into exhaust ports of a multi-cylinder internal combustion engine on an automobile to cause additional combustion therein for purification of exhaust gas prior to its discharge into the atmosphere.
A device typically known in the art for supplying additional combustion air into exhaust ports of a multi-cylinder internal combustion engine on an automobile comprises a main pipe communicating with a source of air supply and a plurality of branch pipes each extending from the main pipe into an air bore which is provided in a cylinder head and communicates with one of the exhaust ports. The main pipe is secured to the cylinder head by union joints. The device is, thus, complicated in construction and any dimensional inaccuracies caused during the manufacture of the device often makes it difficult to properly align each of the branch pipes with the corresponding air bore in the cylinder head. The device is often very difficult to install on the cylinder head properly, and once it is installed, it is difficult to detach the device as the necessity arises. The branch pipes are usually joined to the main pipe by welding and this welding work requires a considerably large amount of time and labor. Connection of the branch pipes into the respective air bores in the cylinder head is an additional time- and labor-consuming job. Furthermore, the length of the branch pipes means a corresponding wasteful increase in the space occupied by the device in the automobile engine compartment.